1. Field of the Invention
The present invention relates broadly to metering and sampling of gravity pressure solution overflows and particularly to the recovery of silver from solutions containing silver and to gravity flow silver and like recovery units and related methods for the foregoing purpose, the apparatus novelly comprising a device for metering the amount of flow of solution through the silver recovery unit and for taking a representative sample of the solution for subsequent analysis so that the efficiency of the silver recovery unit may be readily and accurately determined.
2. Prior Art
Heretofore, silver recovery apparatus has been provided whereby silver may be recovered from solutions containing silver by causing the solution to flow by gravity through a recovery unit in which metal screen or the like is disposed for contact with the solution, so that an ionic exchange occurs precipitating the silver as sludge within the unit. However, previously proposed silver recovery units made no provision for metering and sampling the solution from which silver is recovered. Accordingly, it has not been possible to reliably and accurately assess both the honestly of personnel processing the silver and the efficiency of the silver recovery unit. Consequently, many silver recovery units have been inefficient, and valuable silver has remained in the effluent solution.
The aforesaid situation has been particularly acute in photographic developing laboratories, where spent photographic developing (fixing) solutions contain significant amounts of silver in the form of silver nitrate. A definite need, long standing in the art, has existed for a silver recovery apparatus which meters and samples the solution to evaluate the efficiency of recovery as well as the honesty of the persons handling the recovery.